The disclosures herein relate generally to computer systems and more particularly to an apparatus and method for reducing impact-induced shock and vibration in a portable computer.
Electronic devices such as portable computers, personal digital assistants and portable telephones typically have relatively expensive impact-sensitive components that must be protected from harmful mechanical vibration and shock. In many types of portable electronic devices, impact to the enclosure of the device can result in harmful mechanical vibration and shock. The shock and vibration can adversely affect the performance of many components in a portable computer, including the hard drive, flat panel display and other shock-sensitive components. If the impact is great enough, one or more of the heads in the hard drive may experience an impact-induced head crash. An impact-induced head crash occurs when the actuator arm collides against the surface of an adjacent disk. A head crash may damage the head or the disk, resulting in reduced performance and reliability. The damage may result in immediate failure or undetected damage leading to a shortened operating life.
Although impact loadings occur when an electronic device is accidentally dropped, they are also possible when the electronic device is intentionally placed on a support surface. An impact loading sometimes referred to as a xe2x80x98flat slapxe2x80x99 impact often occurs in portable computers when the bottom surface of the enclosure engages a hard flat surface such as the surface of a table. This type of impact occurs even though most portable computers are generally equipped with resilient feet on their bottom surface for offsetting the bottom surface of the enclosure from the support surface. Warping of the bottom surface of the enclosure and the inertia of the heavy internal components of a portable computer contribute to flat slap impact that can damage internal components.
The hard drive of a portable computer is especially susceptible to damage from shocks associated with impact loadings. To reduce the potential for damage to the hard drives in portable computers, attempts have been made at providing damping devices that protect against loads being applied directly to the case of a hard drive. For example, U.S. Pat. Nos. 5,760,998 and 5,703,734 disclose hard drives that incorporate resilient members protruding from the exterior of the drive case to protect against impact loadings from flat drops of the hard drive. U.S. Pat. No. 5,535,092 discloses a hard drive that incorporates resilient members protruding from the corners of the drive case to protect against the case being dropped on a corner. Furthermore, other components in a hard drive may be mounted on resilient bushings to aid in reducing the transmission of shock and vibration to adjacent components of the hard drive and computer.
A feature commonly referred to as a strike zone has also been used to reduce the adverse effects of flat slap impacts in portable computers. The strike zone is a raised protrusion formed in a metal support member and sometimes in an adjacent portion of the plastic enclosure of the portable computer. The intent of the strike zone is to define an energy dissipating point of contact on the bottom of the portable computer. Typically, a peripheral device such as a hard drive is attached to the support member adjacent to the strike zone. The strike zone is intended to absorb and dissipate shock and vibration from an impact for reducing the peak amplitude of the resulting shock and vibration.
Although various attempts have been made to use strike zones to reduce the loadings applied to the internal components in a portable computer, only limited success has been achieved. Accordingly, there is a need for an improved strike zone configuration that provides greater reduction of impact related shock and vibration in a portable computer without any appreciable increase in manufacturing cost.
One embodiment, accordingly, provides a portable computer including a strike zone having a recessed region for providing improved dissipation of shock and vibration associated with impact loadings. To this end, one embodiment provides an apparatus for dissipating impact energy in a computer system. The apparatus includes a support member including a base wall and a protrusion in the base wall of the support member. The protrusion is offset from the base wall by a first distance. A recess in the protrusion is offset from the base wall by a second distance. The second distance is less than the first distance.
A principal advantage of this embodiment is that the potential for impact related failures of components in a portable computer is greatly reduced.